Dispensing assembly with shut off valve, backflow preventer, and methods of operating the same

Abstract

A dispensing assembly for dispensing a mixture of fluids is provided. In some embodiments, the dispensing assembly includes a first valve for selectively permitting fluid flow to a mixing chamber in which a second fluid is introduced, wherein the valve is actuated between open and closed positions responsive to fluid pressure downstream of the mixing chamber. In such embodiments, the fluid pressure downstream of the mixing chamber can change based upon whether fluid is dispensed from a spray gun, wand, nozzle, or other dispensing head of the dispensing assembly.

What is claimed is: 
     
       1. A dispensing assembly for dispensing at least one fluid, the dispensing assembly comprising:
 a source of a first fluid; 
 a valve having opened and closed positions in which the valve permits and inhibits flow of the first fluid, respectively; 
 a source of a second fluid; 
 a first chamber in fluid communication with the source of the first fluid via the first valve, and in fluid communication with the source of the second fluid; 
 a dispenser outlet through which the first and second fluids are dispensed from the dispenser assembly, the dispenser outlet having opened and closed states in which flow of the first and second fluids from the dispenser outlet is permitted and inhibited, respectively; and 
 a second chamber in fluid communication with the first chamber; 
 the first valve movable from the opened position to the closed position responsive to a change in fluid pressure within the second chamber, and movable from the closed position to the opened position responsive to an opposite change in fluid pressure within the second chamber. 
 
     
     
       2. The dispensing assembly of  claim 1 , wherein the first valve is movable under magnetic force from the closed position to the opened position responsive to the opposite change in fluid pressure. 
     
     
       3. The dispensing assembly of  claim 1 , wherein the first valve comprises a piston. 
     
     
       4. The dispensing assembly of  claim 3 , further comprising a magnet coupled to the piston and positioned to attract another part of the first valve in at least one position of the piston. 
     
     
       5. The dispensing assembly of  claim 4 , wherein the magnet defines at least part of the piston. 
     
     
       6. The dispensing assembly of  claim 4 , wherein the piston is spring-biased. 
     
     
       7. The dispensing assembly of  claim 1 , further comprising a second valve having opened and closed positions in which the second valve permits and inhibits flow of the second fluid, respectively, into the first chamber. 
     
     
       8. The dispensing assembly of  claim 1 , wherein the second chamber is a venturi chamber. 
     
     
       9. The dispensing assembly of  claim 1 , further comprising a flow sensing valve having opened and closed positions in which the second valve permits and inhibits flow of the second fluid, respectively, into the first chamber. 
     
     
       10. The dispensing assembly of  claim 9 , wherein the flow sensing valve includes a flexible diaphragm.